Generally, integrated circuit devices are manufactured in such a manner that various kinds of films are formed on the semiconductor substrates. The various kinds of films are formed to have certain ranges of thickness. Accordingly, a film thickness standard (FTS) reference material measuring film thickness is provided and used to control the thickness of the various kinds of films.
The conventional oxide film thickness standard reference has a thickness less than 1 .mu.m. The oxide film thickness standard reference having a thickness of less than 1 .mu.m is described in detail in the catalogue of VLSI Standards Incorporated 1996 Product Guide.
However, the above oxide film standard thickness reference having a thickness below 1 .mu.m may not be sufficient to calibrate state of the art thin film manufacturing including an oxide film over 1 .mu.m thick.
Unfortunately, it may be difficult to fabricate oxide film thickness standards having a thickness over 1 .mu.m without defects such as uniformity variations. Thus, it generally is difficult to set up process conditions to prepare the oxide film thickness standard reference having a thickness over 1 .mu.m.